European anatomists started to figure out the distinction by making side-by-side comparisons. The teeth of mammoths and modern elephants both have relatively flat running-shoe corrugations on the biting surface. But the teeth of the incognitum are studded with fierce-looking rows of large conical cusps. That difference not only indicated that Siberian mammoths and the incognitum were separate species, it also led some anatomists to regard the latter as a flesh-eating monster.

“Though we may as philosophers regret it,” the British anatomist William Hunter wrote in 1768, “as men we cannot but thank Heaven that its whole generation is probably extinct.” Benjamin Franklin, then on diplomatic duty in London, observed that the animal’s big tusks would have been an impediment “for pursuing and taking Prey.” Ever the practical thinker, he suggested that those fierce-looking teeth might be “as useful to grind the small branches of Trees, as to chaw Flesh”—and he was right. We now know that mammoths predominated in the open grasslands of the American West and in Siberia, where they needed flat teeth for eating grass. The incognitum, a smaller animal with less curvature to its tusks, lived mostly in the heavy forests east of the Mississippi River and browsed on tree branches.

Those teeth also eventually gave the incognitum a name. To the young French anatomist Georges Cuvier, the conical cusps looked like breasts. So in 1806, he named the incognitum “mastodon,” from the Greek mastos (for “breast”) and odont (for “tooth”). But laymen went on applying the name “mammoth” to either species—and to just about anything else really big.

The discovery of such monstrous creatures raised troubling questions. Cuvier made the case that both mammoths and mastodons had vanished from the face of the earth; their bones were just too different from any known pachyderm. It was the first time the scientific world accepted the idea that any species had gone extinct—a challenge to the doctrine that species were a permanent, unchanging heritage from the Garden of Eden. The disappearance of such creatures also cast doubt on the idea that the earth was just 6,000 years old, as the Bible seemed to teach.

In fact, mammoths and mastodons shook the foundations of conventional thought. In place of the orderly old world, where each species had its proper place in a great chain of being, Cuvier was soon depicting a chaotic past in which flood, ice and earthquake swept away “living organisms without number,” leaving behind only scattered bones and dust. That apocalyptic vision of the earth’s history would haunt the human imagination for much of the 19th century.

At the same time, mammoths and mastodons gave Americans a symbol of national might at a time when they badly needed one.

Georges-Louis Leclerc, Comte de Buffon, the French naturalist, had declared that “a niggardly sky and an unprolific land” caused species in the New World—including humans—to become puny and degenerate. “No American animal can be compared with the elephant, the rhinoceros, the hippopotamus,” he sniffed in 1755. Even the American Indian is “small and feeble. He has no hair, no beard, no ardour for the female.” Because Buffon was one of the most widely read authors of the 18th century, his “theory of American degeneracy” became conventional wisdom, at least in Europe.

Clearly offended, Thomas Jefferson (who stood 6-foot-2) constructed elaborate tables comparing American species with their puny Old World counterparts—three-and-a-half pages of bears, bison, elk and flying squirrels going toe-to- toe. In the early 1780s, he wrote that the mammoth, “the largest of terrestrial beings,” should have “stifled in its birth” Buffon’s notion “that Nature is less active, less energetic on one side of the globe than she is on the other. As if both sides were not warmed by the same genial sun; as if a soil of the same chemical composition was less capable of elaboration into animal nutriment.” When Jefferson sailed to Paris in 1784 to represent the new United States, he packed “an uncommonly large panther skin” with the idea of shaking it under Buffon’s nose. He later followed up with a moose. (Buffon promised to amend his errors in the next edition of his book, according to Jefferson, but died before he could do so.)

It wasn’t just a matter of wounded pride. For American envoys in the 1770s and ’80s, refuting the idea of innate inferiority was essential “if they were to obtain sorely needed financial assistance and credit in Europe,” says anthropologist Thomas C. Patterson. And they took every opportunity to make their point. Once, at a dinner in Paris, a diminutive Frenchman (in recounting the story, Jefferson described him as “a shrimp”) was enthusiastically preaching the doctrine of American degeneracy. Benjamin Franklin (5-foot-10) sized up the French and American guests, seated on opposite sides of the table, and proposed: “Let us try this question by the fact before us.... Let both parties rise, and we will see on which side nature has degenerated.” The Frenchmen muttered something about exceptions proving rules.

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